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B. A. Rowland, W. Jiang, B. E. Stein; Cortical Afferents of the Superior Colliculus Guide the Development of Multisensory Integration in Visual Localization. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3763.
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Here we show that this capacity is impaired in animals (cats) whose corticical inputs to the SC from the anterior ectosylvian (AES) and rostrolateral suprasylvian sulci (rLS) were temporarily deactivated during early life.
Cortical regions AES and rLS were deactivated between 4-12 wks postnatal using Elvax polymer infused with the GABAa agonist muscimol. Beginning at 1 year of age, the animals were trained to localize visual stimuli and ignore auditory stimuli that appeared at various locations in a semi-circular perimetry device. Visual intensities were then lowered until the accuracy of visual localization was reduced to 30-50% at each location. The animals were then tested with unisensory visual; unisensory auditory; and multisensory (visual-auditory) stimuli at each location.
The coincident auditory stimulus facilitated localization of the visual target in ipsilesional space (i.e., multisensory integration was intact); however, it failed to facilitate visual localization in contralesional space.
These findings suggest that the development of normal multisensory integration requires not only the structural integrity of cortico-SC afferents as previously shown, but their active participation during a developmental sensitive period. The results support the theory that multisensory integration develops as a consequence of the cortico-collicular afferents acquiring experience during early life.
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